What's the angle on the master cylinder on the W113? Fairly flat or canted upwards a bit?

I don't believe you should have air in there either, but something is wrong. Again, I'd check to make sure that you can generate pressure at the master cylinder itself before going further, you will just be chasing your tail.

Fixed the problem on my brother's truck -- he's loosened the lines on the master cylinder to change it before we found the bad wheel cylinders in the back, and forgot to tighten them. Works much better now, no fluid leaks, either.

You should be able to gravity bleed the fronts, at least, so something screwy is going on here.

You must have master cylinder piston travel, or you wouldn't get fluid pushed out of the calipers, and if they were all stuck (very unlikely) you would have a nice hard pedal!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!